I was going to say that Twitter isn't the most representative because of its relatively small uptake, but then I checked and was surprised to find out that ~20% of people use twitter:
But I would expect that older crotchety suburban drivers are less likely to use twitter than single urban 20-somethings who live downtown and take the streetcar, and the people who tweet about the King street pilot are more likely to be transit users currently sitting in said streetcar instead of drivers trying to navigate the new maze of turn restrictions.
So, still not necessarily representative of general sentiment, just of the twitterverse's demographic bubble.
Twitter is pretty niche in Toronto. The US is largely responsible for that 21% — if anything, Canada is dragging the number down. All of my US friends or clients are on Twitter and TV channels in the US almost always list someone's Twitter handle.
That said, Twitter has been a great place for #KingStreetPilot discussion and I've been told that city officials have been monitoring it closely and taking notes for improvements.